<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html
        PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
    <title>Title</title>
</head>
<body>
    <select name="city">
    <optgroup label="分组">
        <option value="1">北京</option>
        <option value="2">上海</option>
    </optgroup>
    <option value="3" selected="selected">南京</option>
    <option value="4">苏州</option>
</select>
<select name="city" size="5" multiple="multiple">
    <optgroup label="分组">
        <option value="1">北京</option>
        <option value="2">上海</option>
    </optgroup>
</select>
</body>
</html>